Enamelled metallic wires

ABSTRACT

The invention relates to varnished metal wires with one or more electrically insulating varnish coatings, at least one of the electrically insulating varnish coatings representing an organically modified silicic acid (hetero) polycondensate, which has been obtained by partial or total hydrolytic condensation of one or more hydrolytically condensable compounds of silicon and if necessary other elements from the group B, A1, P, Sn, Pb, the transition metals, the lanthanides and actinides, and/or from precondensates derived from the abovenamed compounds, if necessary in the presence of a catalyst and/or of a solvent by the action of water and moisture.

The invention relates to varnished metal wires upon which there areapplied one or more electrically insulated varnish coatings. Suchvarnish-insulated wires, which in particular consist of copper, havebeen used for a long time for the manufacture of windings of electricalmotors and other coils. The applied varnish coating in this case, inaddition to providing protection against mechanical influences, is alsointended to have an insulating effect. The varnish layer, or a pluralityof varnish layers to be applied one above the other, are applied withapplicator systems specially developed for this purpose, the solventcontained in the varnish being removed by a thermal treatment. In thisthermal treatment at the same time the organic resins are hardened bypolycondensation. The polymer systems used until now on a polyimide orpolyamide basis are however not always suitable to resist the mechanicalstresses occurring, such in particular as occur during winding of coilsor other elements.

Improved scratch resistance and adhesion and a greater resistance toscraping stress and thus higher abrasion resistance are required.

The coated metal wires must also however be sufficiently flexible withthe coating applied, and the coating must not crack during bending andthe corresponding partial stretching along the bending radius. A highpartial discharge stability is also an important criterion.

Moreover, the applied varnish layers or plurality of varnish layersapplied one above the other must also have the desired properties evenat relatively high temperatures, and no harmful materials must be givenoff during heating.

In order to reduce costs during the manufacture of such varnished metalwires, high hardening speeds must be achieved in order to shorten thenecessary coating and in order to keep small the necessary outlay onspace for the coating systems. From the environmental point of view itis also necessary to use coating materials which contain no solvents ornon-toxic and non-aggressive solvents.

It is therefore the object of the invention to provide varnished metalwires with one or a plurality of electrically insulating varnishcoatings, ensuring a high hardening speed with simultaneous improvementin the mechanical, thermal and electrical properties of the appliedvarnish coatings.

In contrast to those previously used, the electrically insulatingvarnish layers applied according to the invention contain no criticalsolvents, such as xylols, cresols, NMP or others, so that during coatingand during hardening there are no further requirements as regards anexpensive evacuation system and filtering of the evacuated gases. As inthe case of the varnish layers applied, as a rule the organicallypolymerisable groups are compounded with the inorganic polymerstructure, no toxicologically problematic monomers such for example asacrylate monomers, occur.

The coating may be extremely flexible in structure by means of variousmethods; they may be applied for example by extrusion with highproductivity and the smallest losses. In one coating step, considerablylarger coating thicknesses can be applied than is possible with previousmethods and wire varnishes previously used. Thus, in one coatingprocedure, a coating thickness can be applied which previously was onlyachieved with ten successively applied coats. The coating thicknessshould be in a range between 2 and 100 μm and preferably between 5 and30 μm.

The most varied methods and energies may be used for hardening; thushardening may be carried out for example with UV, IR, normal light orthermal procedures, or with the combination of a plurality of energyforms. As the hardening speeds of the IR or photo-induced hardening lieconsiderably above the thermal ones, the corresponding varnish systemsare preferred. In this way in all there results a higher applicationspeed.

A further advantage is the great variability in the composition of thevarnish layer, which can be co-ordinated to the most varied mechanicalrequirements and correspondingly optimised. Thus, for the most variedcases of application, the abrasion resistance, scratch resistance,hardness, flexibility, tensile strength, adhesion and expansion capacitycan be correspondingly optimised for all or special properties.

A further advantage arises from the achievement of a relatively highoverall cross linking density, which ensures high tan δ-transitiontemperatures and the inorganic molecule portion ensures a high partialdischarge stability, such as for example are necessary with electricmotors.

The electrical properties are also favourable, as high disruptivestrengths and high volume resistances can be achieved with the appliedvarnish layers.

The varnished metal wires according to the invention are considerablyimproved in their properties compared to the previously-used varnishlayers, as in particular normally mutually exclusive requirements, suchfor example as high scratch resistance (scraping resistance) and a hightensile strength or expansion capacity cannot normally be optimallytaken into account within wide temperature ranges.

In addition, one or more layers of other materials or mixtures ofmaterials can be applied.

The coating may be applied to the most varied metal, such as copper,gold, silver, aluminum, tin, zinc or iron or alloys.

The varnished metal wire according to the invention will be coated witha varnish which has been obtained by partial or total hydrolyticcondensation of one or a plurality of hydrolytically condensablecompounds of silicon and if necessary other elements from the group B,Al, P, Sn, Pb, the transitional metals, the lanthanides and theactinides, and/or from the precondensates derived from the abovenamedcompounds, if necessary in the presence of a catalyst and/or of asolvent by the action of water or moisture. This varnish can be appliedto metal wires, which if necessary already have one or more electricallyinsulating varnish coats, and can if necessary be subsequently dried andhardened.

It is advantageous to apply at least two varnish layers, which representan organically modified silicic acid (hetero) polycondensate.

The organically modified silicic acid (hetero) polycondensate to be usedaccording to the invention can contain one or more hydrolytically(pre)-condensed compounds of silicon, which are derived from variousmonomers. These coating materials are known under the name ORMOCERs.Express reference is made here to the disclosed content of U.S. Pat. No.5,399,738; 5,532,398; 5917,075; and 6,124,491.

Examples of such monomers, which are derivable from general formulae,are:

I.

{X_(a)R_(b)Si[(R′A)_(c)]_((4−a−b))}_(x)B  (I)

The residues and indices being identical or different, and having thefollowing meaning:

A = O, S, PR″, POR″, NHC(O)O or NHC(O)NR″, B = a straight-chained orbranched organic residue, derived from a compound BI with at least one(for c = 1 und A = NHC(O)O or NHC(O)NR″) or atleast two C = C-doublebonds and 5 to 50 carbon atoms, R = alkyl, alkenyl, aryl, alkylaryl orarylalkyl, R′ = alkylene, arylene or alkylenarylene, R″ = hydrogen,alkyl or aryl, X = hydrogen, halogen, hydroxy, alkoxy, acyloxy,alkylcarbonyl, alkoxycarbonyl or NR″₂, a = 1, 2 or 3, b = 0, 1 or 2, c =0 or 1, x = a whole number, whose maximum value corresponds to thenumber of double bonds in the compound B′ minus 1, or is equal to thenumber of double bonds in the compound B′, if c = 1 and A stands forNHC(O)O or NHC(O)NR″,

the alkyl or alkenyl residues if necessary being substitutedstraight-chained, branched or cyclic residues with 1 to 20 carbon atomsand being capable of containing oxygen and/or sulphur atoms and/or aminogroups, aryl stands for if necessary substituted phenyl, naphthyl orbiphenyl, and the above alkoxy-, acyloxy-, alkylcarbonyl-,alkoxycarbonyl-, alkylaryl-, arylalkyl-, arylene-, alkylene andalkylenearyl residues are derived from the above-defined alkyl- and arylresidues.

An advantageous feature in a varnish system based on these silanes isthat in this way there is a possibility of bonding to inorganic surfaces(e.g. Cu). The hardening can be influenced by the variability in thenumber of reactive double bonds.

II.

here the residues and indices being identical or different, and have thefollowing meaning:

B = a straight-chained or branched organic residue with at least one C =C-double bond and 4 to 50 carbon atoms; X = hydrogen, halogen, hydroxy,alkoxy, acyloxy, alkylcarbonyl, alkoxycarbonyl or NR″₂; R = alkyl,alkenyl, aryl, alkylaryl or arylalkyl; R′ = alkylene, arylene,arylenealkylene or alkylenearylene with respectively 0 to 10 carbonatoms, these residues being capable of containing oxygen and/or sulphuratoms and/or amino groups; R″ = hydrogen, alkyl or aryl; A = O, S or NHfor d = 1 and Z = CO and R¹ = if necessary alkylene, arylene oder al-kylenearylene containing oxygen- and/or sulphur atoms and/oramino-groups, with 1 to 10 carbon atoms respectively, and R² = H orCOOH; or A = O, S, NH or COO for d = 0 or 1 and Z = CHR, with R = H,alkyl, aryl or alky- laryl, and R¹ = alkylene, arylene oralkylenearylene if necessary interrupted by oxygen or sulphur atoms,with 1 to 10 carbon atoms respectively, and R² = OH; or A = S for d = 1and Z = CO and R¹ = N and R² = H; a = 1, 2 or 3; b = 0, 1 or 2, with a +b = 3; c = 1, 2, 3 or 4.

An advantage in this case of R²=CO₂H, that for example a complexing ofmetal atoms of the wire surface can be achieved. In this way anextremely stable bond results.

III.

In this case the residues and indices can be identical or different andhave the following meaning:

X = hydrogen, halogen, hydroxy, alkoxy, acyloxy, alkylcarbonyl,alkoxycarbonyl or NR² ₂; R = alkyl, alkenyl, aryl, alkylaryl orarylalkyl; R′ = alkylene, arylene, arylenealkylene or alkyle- nearylenewith respectively 0 to 10 carbon atoms, these residues being capable ofcontaining oxygen- and/or sulphur atoms and/or amino groups; R″ =alkylene, arylene, arylenealkylene or alkylenearylene with respectively1 to 10 carbon atoms, these residues being capable of containing oxygenand/or sulphur atoms and/or amino groups; R² = hydrogen, alkyl or aryl;a = 1, 2 oder 3; b = 0, 1 or 2, with a + b = 1, 2 or 3; c = 1, 2, 3, 4,5 or 6; d = 4 − a − b.

An advantage in this system is that the R¹⁽¹¹⁾—O group can react uponring opening, e.g. with amino groups, so that likewise a stable bondresults.

The invention will be explained in the following with reference tofurther examples.

I EXAMPLES OF THE USE OF VARIOUS ORMOCER SYSTEMS AS TOP COAT

There were used copper wire with a Teic-polyesterimide basic layer(coating thickness=30 μm). The following varnish systems quoted wereapplied as a cover varnish (top coat) and were thermally hardened. At600° C., in dependence on the furnace length, wire speeds of well above25 m/min are possible. There result coatings with excellent surfacequality. Condensation water stability (14 days at 40° C. and 100%relative air humidity) is also provided, as is a high resistance tothermal shock (freedom from cracks after 10 to 30 s, 300° C.). Anextremely good bond to the Teic-polyesterimide basic coating, i.e.extremely good adhesion is observed (in REM photographs no phaseboundary layer is visible any longer). Further detailed data are quotedin the individual examples.

In the examples the following abbreviations are used:

SR-368=tris-(2-hydroxyethyl) isocyanuratetriacrylate

MPMDM=3-mercaptopropylmethyldimethoxysilane

TEOS=tetraethoxysilane

TMPTA=trimenthypropanetriacrylate

MMDO=mercaptopropylmethyldimethoxysilane

DDDM=dodecanediolmethacrylate

Example 1 SR-368: MPMDM=1:1

54.0 g (0.3 mol) of 3-mercaptopropylmethyldimethoxysilane are drippedinto the receiver of 127 g (0.3 mol) tris-(2-hydroxyethyl)isocyanuratetriacrylate, dissolved in 300 ml ethyl acetate. Withcooling, 19 g of an ethanolic KOH solution is slowly dripped in. Afterabout 5 minutes the reaction (thiol addition to an acrylate double bond)is terminated. 8.6 g of 0.5 n HCL is dripped in to hydrolyse andcondense the methoxy groups. After stirring at ambient temperature forabout 1 day, the mixture is processed. The resultant varnish can beused, directly or after modification of the solvent content orcomposition, to adjust the rheology for wire coating. The followingproperties result on a Cu wire with a diameter=0.95 mm:

coating thickness: about 11 μm

tan δ-glass transition temperature (DIN) about 202° C.

1×D−winding curl=crack-free

windable

Example 2 SR-368: MPMDM:TEOS=1:1:0.2

14.4 g(0.08 mol) of mercaptopropylmethyldimethoxysilane are dripped intothe receiver of 33.8 g (0.08 mol) tris-(2-hydroxyethyl)isocyanuratetriacrylate, dissolved in 80 ml ethyl acetate. With cooling,5.1 g of an ethanolic KOH solution is slowly dripped in. After about 5minutes the reaction (thiol addition to an acrylate double bond) isterminated. 2.3 g of 0.5 n HCL is dripped in to hydrolyse and condensethe methoxy groups. After stirring at ambient temperature for about 5hours, 3.33 g (0.016 mol) of tetraethoxysilane and 0.92 g of 0.12 n HCLare added. After further stirring at ambient temperature for about 1day, the mixture is processed. The resultant varnish can be used,directly or after modification of the solvent content or composition, toadjust the rheology for wire coating. The following properties result ona Cu wire with a diameter=0.95 mm:

coating thickness: about 19 μm

1×D−winding curl=crack-free

windable

Example 3 SR-368: MPMDM:TEOS=1:1:0.4

27.0 g (0.15 mol) of mercaptopropylmethyldimethoxysilane are drippedinto the receiver of 63.50 g (0.15 mol) tris-(2-hydroxyethyl)isocyanuratetriacrylate, dissolved in 150 ml ethyl acetate. Withcooling, 9.7 g of an ethanolic KOH solution is slowly dripped in. Afterabout 5 minutes the reaction (thiol addition to an acrylate double bond)is terminated. 4.4 g of 0.5 n HCL is dripped in to hydrolyse andcondense the methoxy groups. After stirring at ambient temperature forabout 5 hours, 12.5g (0.06 mol) of tetraethoxysilane and 3.5 g of 0.12 nHCL are added. After further stirring at ambient temperature for about 1day, the mixture is processed. The resultant varnish can be used,directly or after modification of the solvent content or composition, toadjust the rheology for wire coating. The following properties result ona Cu wire with a diameter=0.95 mm or 0.32 mm:

coating thickness: about 15 μm

1×D−winding curl=crack-free

windable

Example 4 TMPTA: MPMDM =1:1

45 g (0.25 mol) of 3-mercaptopropylmethyldimethoxysilane are drippedinto the receiver of 74 g (0.25 mol) trimethylpropanetriacrylate,dissolved in 250 ml ethyl acetate. With cooling, 15.8 g of an ethanolicKOH solution is slowly dripped in. After about 5 minutes the reaction(thiol addition to an acrylate double bond) is terminated. 4.5 g of 0.7n HCL is dripped in to hydrolyse and condense the methoxy groups. Afterstirring at ambient temperature for about 1 day, the mixture isprocessed. The resultant varnish can be used, directly or aftermodification of the solvent content or composition, to adjust therheology for wire coating. The following properties result on a Cu wirewith a diameter=0.95 mm:

coating thickness: about 8 μm

tan δ-glass transition temperature (DIN): about 215° C.

scraping force: about 17 N

Example 5 SR-368: MPMDM=1:1.2

64.9 g (0.36 mol) of 3-mercaptopropylmethyldimethoxysilane are drippedinto the receiver of 127 g (0.3 mol) tris-(2-hydroxyethyl)isocyanuratetriacrylate, dissolved in 360 ml ethyl acetate. Withcooling, 22.8 g of an ethanolic KOH solution is slowly dripped in. Afterabout 5 minutes the reaction (thiol addition to an acrylate double bond)is terminated. 10.4 g of 0.5 n HCL is dripped in to hydrolyse andcondense the methoxy groups. After stirring at ambient temperature forabout 1 day, the mixture is processed. The resultant varnish can beused, directly or after modification of the solvent content orcomposition, to adjust the rheology for wire coating. The followingproperties result on a Cu wire with a diameter=0.95 mm:

coating thickness: about 9 μm

tan δ-glass transition temperature (DIN) about 205° C.

scraping force about 15 N

1×D−winding curl=crack-free

windable

Example 6 SR-368: MPMDM=1:1.2 (with filler)

64.9 g (0.36 mol) of 3-mercaptopropylmethyldimethoxysilane are drippedinto the receiver of 127 g (0.3 mol) tris-(2-hydroxyethyl)isocyanuratetriacrylate, dissolved in 360 ml ethyl acetate. Withcooling, 22.8 g of an ethanolic KOH solution is slowly dripped in. Afterabout 5 minutes the reaction (thiol addition to an acrylate double bond)is terminated. 10.4 g of 0.5 n HCL is dripped in to hydrolyse andcondense the methoxy groups. After stirring at ambient temperature forabout 1 day, the mixture is processed, and 20% by weight of microfineglass GM 32087 (silanised) is added. The resultant varnish can be used,directly or after modification of the solvent content or composition, toadjust the rheology for wire coating. The following properties result ona Cu wire with a diameter=0.95 mm:

coating thickness: about 9 μm

tan δ-glass transition temperature. (DIN) about 206° C.

scraping force about 17.5 N

1×D−winding curl=crack-free

windable

Example 7 SR-368: MMDO=1:1

72.1 g (0.36 mol) of mercaptopropylmethyldimethoxysilane are drippedinto the receiver of 169 g (0.4 mol) tris-(2-hydroxyethyl)isocyanuratetriacrylate, dissolved in 400 ml ethyl acetate. Withcooling, 25.3 of an ethanolic KOH solution is slowly dripped in. Afterabout 5 minutes the reaction (thiol addition to an acrylate double bond)is terminated. 11.5 g of 0.5 n HCL is dripped in to hydrolyse andcondense the methoxy groups. After stirring at ambient temperature forabout 1 day, the mixture is processed. The resultant varnish can beused, directly or after modification of the solvent content orcomposition, to adjust the rheology for wire coating. The followingproperties result on a Cu wire with a diameter=0.95 mnm:

coating thickness: about 11 μm

tan δ-glass transition temperature. (DIN) about 205° C.

scraping force about 23 N

II EXAMPLES OF THE USE OF VARIOUS ORMOCER SYSTEMS AS A FULL COAT

There were used copper wires (Ø=0.32 mm) without a Teic-polyesterimidebasic layer. The following coated varnish systems were thus applied as acoat and thermally hardened. At e.g. 370° C. wire speeds in dependenceon the furnace length of well above 14 m/min are possible. There resultcoatings with excellent surface quality. An extremely good bond with thewire surface, i.e. excellent adhesion is observed. Further detailed dataare quoted in the individual examples.

Example 8 SR-368: MPMDM:TEOS=1:1:0.4

27.0 g (0.15 mol) of 3-mercaptopropylmethyldimethoxysilane are drippedinto the receiver of 63.5 g (0.15 mol) tris-(2-hydroxyethyl)isocyanuratetriacrylate, dissolved in 150 ml ethyl acetate. Withcooling, 9.7 g of an ethanolic KOH solution is slowly dripped in. Afterabout 5 minutes the reaction (thiol addition to an acrylate double bond)is terminated. 4.4 g of 0.5 n HCL is dripped in to hydrolyse andcondense the methoxy groups. After stirring at ambient temperature forabout 5 hours, 12.5 g (0.06 mol) of tetraethoxysilane and 3.5 g of 0.12n HCL are added. After further stirring at ambient temperature for about1 day, the mixture is processed. The resultant varnish can be used,directly or after modification of the solvent content or composition, toadjust the rheology for wire coating. The following properties result:

coating thickness: about 10 μm

1×D−winding curl crack-free

windable

Example 9 SR-368: MPMDM:TEOS=1:1:0.5

90 g (0.5 mol) of 3-mercaptopropylmethyldimethoxysilane are dripped intothe receiver of 212 g (0.5 mol) tris-(2-hydroxyethyl)isocyanuratetriacrylate, dissolved in 500 ml ethyl acetate. Withcooling, 32.2 g of an ethanolic KOH solution is slowly dripped in. Afterabout 5 minutes the reaction (thiol addition to an acrylate double bond)is terminated. 14.7 g of 0.5 n HCL is dripped in to hydrolyse andcondense the methoxy groups. After stirring at ambient temperature forabout 5 hours, 52 g (0.25 mol) of tetraethoxysilane and 14.8 g of 0.12 nHCL are added. After further stirring at ambient temperature for about 1day, the mixture is processed. The resultant varnish can be used,directly or after modification of the solvent content or composition, toadjust the rheology for wire coating. The following properties result:

coating thickness: about 10 μm

1×D−winding curl=crack-free

windable

Example 10 SR-368: MPMDM:TEOS:DDDM=1:1:0.4:0.3 (solvent-freeapplication)

90 g (0.5 mol) of 3-mercaptopropylmethyldimethoxysilane are dripped intothe receiver of 212 g (0.5 mol) tris-(2-hydroxyethyl)isocyanuratetriacrylate, dissolved in 500 ml ethyl acetate. Withcooling, 32.2 of an ethanolic KOH solution is slowly dripped in. Afterabout 5 minutes the reaction (thiol addition to an acrylate double bond)is terminated. 14.7 g of 0.5 n HCL is dripped in to hydrolyse andcondense the methoxy groups. After stirring at ambient temperature forabout 5 hours, 52 g (0.25 mol) of tetraethoxysilane and 14.8 g of 0.12 nHCL are added. After further stirring at ambient temperature for about 1day, the mixture is processed, 3.2 g (0.15 mol)dodecandioldimethacrylate are added and the solvent withdrawn by meansof a rotary evaporator. The resultant varnish can be used directly forwire coating.

Example 11 SR-368: MPMDM:TEOS=1:1:0.5

13 g (0.072 mol) of 3-mercaptopropylmethyldimethoxysilane are drippedinto the receiver of 30.5 g g (0.072 mol) tris-(2-hydroxyethyl)isocyanuratetriacrylate, dissolved in 70 ml ethyl acetate. With cooling,4.6 g of an ethanolic KOH solution is slowly dripped in. After about 5minutes the reaction (thiol addition to an acrylate double bond) isterminated. 14.7 g of 0.5 n HCL is dripped in to hydrolyse and condensethe methoxy groups. After stirring at ambient temperature for about 5hours, 7.0 g (0.036 mol) of tetraethoxysilane and 2.14 g of 0.12 n HCLare added. After further stirring at ambient temperature for about 1day, the mixture is processed. The resultant varnish can be used,directly or after modification of the solvent content or composition, toadjust the rheology for wire coating. The following properties result:

coating thickness: about 9 μm

1×D−winding curl=crack-free

scraping force >8 N

windable

Example 12 SR-368: MPMDM:TEOS=1:1:1:0.5

21.6 g (0.120 mol) of 3-mercaptopropylmethyldimethoxysilane are drippedinto the receiver of 56.3 g (0.133 mol) tris-(2-hydroxyethyl)isocyanuratetriacrylate, dissolved in 100 ml ethyl acetate. Withcooling, 7.9 g of an ethanolic KOH solution is slowly dripped in. Afterabout 5 minutes the reaction (thiol addition to an acrylate double bond)is terminated. 3.53 g of 0.5 n HCL is dripped in to hydrolyse andcondense the methoxy groups. After stirring at ambient temperature forabout 5 hours, 12.5 g (0.06 mol) of tetraethoxysilane and 3.52 g of 0.12n HCL are added. After further stirring at ambient temperature for about1 day, the mixture is processed. The resultant varnish can be used,directly or after modification of the solvent content or composition, toadjust the rheology for wire coating. The following properties result:

coating thickness: about 9 μm

1×D−winding curl=crack-free

windable

What is claimed is:
 1. A varnished metal coil wire with one or moreelectrically insulating varnish coatings, wherein at least one of theelectrically insulating varnish coatings comprises an organicallymodified silicic acid (hetero) polycondensate, which has been obtainedby partial or total hydrolytic condensation of at least one of (a) oneor more hydrolytically condensable compounds of silicon or of siliconand of elements selected from the group consisting of B, Al, P, Sn, Pb,transition metals, lanthanides and actinides; and (b) one or moreprecondensates derived from the compounds mentioned under (a); by theaction of water or moisture, the varnish coatings remaining crack-freewhen the varnished metal coil wire is wound on a core having a diameterequal to the metal wire.
 2. The varnished metal wire according to claim1, wherein the hydrolytic condensation takes place in the presence of atleast one of a catalyst and a solvent.
 3. The varnished metal wireaccording to claim 1, wherein the organically modified silicic acid(hetero) polycondensate comprises one or more hydrolytically condensedor precondensed compounds of silicon, which are derived from monomers ofthe general formula I, {X_(a)R_(b)Si[(R′A)_(c)]_((4−a−b))}_(x)B  (I) inwhich the residues and indices are identical or different and have thefollowing meaning: A=O, S, PR″, POR″, NHC(O)O or NHC (O) NR″, B=astraight-chained or branched organic residue, derived from a compound B′with at least one (for c=1 and A=NHC(O)O or NHC (O)NR″) or at least twoC═C-double bonds and 5 to 50 carbon atoms, R=alkyl, alkenyl, aryl,alkylaryl or arylalkyl, R′=alkylene, arylene or alkylenearylene,R″=hydrogen, alkyl or aryl, X=hydrogen, halogen, hydroxy, alkoxy,acyloxy, alkylcarbonyl, alkoxycarbonyl or NR″_(2′) a=1, 2 or 3 b=0, 1 or2 c=0 or 1, x=a whole number, whose maximum value is equal to the numberof double bonds in the compound B′ minus 1, or is equal to the number ofdouble bonds in the compound B′ if c=1 and A is NHC(O) or NHC(O)NR″, thealkyl or alkenyl residues being substituted or non-substitutedstraight-chained, branched or cyclic residues with 1 to 20 carbon atomsaryl being substituted or non-substituted phenyl, naphthyl or biphenyl,and the above alkoxy, acyloxy, alkylcarbonyl, alkoxycarbonyl, alkylaryl,arylalkyl, arylene, alkylene and alkylenearyl residues being derivedfrom the above-defined alkyl and aryl residues.
 4. The varnished metalwire according to claim 3, wherein the alkyl or alkenyl residuescomprise at least one of the oxygen atoms, sulphur atoms and aminogroups.
 5. The varnish metal wire according to claim 1, wherein theorganically modified silicic acid (hetero) polycondensate comprises oneor more hydrolytically condensed or precondensed compounds or silicon,which are derived from monomers of the general formula II,

in which the residues and indices are identical or different and havethe following meaning: B=a straight-chained or branched organic residuewith at least one C═C-double bond and 4 to 50 carbon atoms; X=hydrogen,halogen, hydroxy, alkoxy, acyloxy, alkylcarbonyl, alkoxycarbonyl orNR″₂; R=alkyl, alkenyl, aryl, alkylaryl or arylalkyl; R′=alkylene,arylene, arylenealkylene or alkylenearylene with 0 to 10 carbon atomsrespectively; R″=hydrogen, alkyl or aryl; A=O, S, or NH for d=1 and Z=COand R¹=alkylene, arylene or alkylenearylene with 1 to 10 carbon atomsrespectively, and R²=H or COOH; or A=O, S, NH or COO for d=0or 1 andZ=CHR, with R=H, alkyl, aryl or alkylaryl, and R¹=alkylene, arylene oralkylenearylene with 1 to 10 carbon atoms respectively, and R²=OH; orA=S for d=1 and Z=CO and R¹=N and R²=H; a=1, 2 or 3; b=0, 1 or 2, witha+b=3; c=1, 2, 3 or
 4. 6. The varnished metal wire according to claim 5,wherein the residue R′ comprises at least one of the oxygen atoms,sulphur atoms and amino groups.
 7. The varnished metal wire according toclaim 5, wherein the residue R′ comprises at least one of oxygen atoms,sulphur atoms and amino groups if R¹ is aklylene, arylene oralkylenearylene.
 8. The varnished metal wire according to claim 1,wherein the organically modified silicid acid (hetero) polycondensatecomprises one or more hydrolytically condensed or precondensed compoundsof silicon, which are derived from monomers of the general formula III,

in which the residues and indices are identical or different and havethe following meaning: X=hydrogen, halogen, hydroxy, alkoxy, acyloxy,alkylcarbonyl, alkoxycarbonyl or NR² ₂; R=alkyl, alkenyl, aryl,alkylaryl or arylalkyl; R′=alkylene, arylene, arylenealkylene oralkylenearylene with 0 to 10 carbon atoms respectively; R″=alkylene,arylene, arylenealkylene or alkylenearylene with 1 to 10 carbon atomsrespectively; R²=hydrogen, alkyl or aryl; a=1, 2 or 3; b=0, 1 or 2, witha+b=1, 2, or 3; c=1, 2, 3, 4, 5 or 6; d=4−a−b.
 9. The varnished metalwire according to claim 8, wherein the residue R′ comprises at least oneof oxygen atoms, sulphur atoms and amino groups.
 10. The varnished metalwire according to claim 8, wherein the residue R″ comprises at least oneof oxygen atoms, sulphur atoms and amino groups.
 11. The varnished metalwire according to claim 1, wherein the varnished metal wire comprises atleast two varnish coatings, containing an organically modified silicicacid (hetero) polycondensate.
 12. The varnished metal wire according toclaim 1, wherein the metal wire comprises a metal selected from thegroup consisting of copper, gold, silver, aluminum, tin, zinc and ironor an alloy of these metals.
 13. The varnished metal wires according toclaim 1, wherein the metal wire comprises one or more varnish layers onat least one of a Teic-polyesterimide basis, a polyimide basis, apolyamide basis and a polyimidoamide basis.
 14. The varnished metal wireaccording to claim 1, wherein the one or more silicic acid (hetero)polycondensate coatings have a thickness between 1 and 100 μm.
 15. Thevarnished metal wire according to claim 1, wherein the one or moresilicid acid (hetero) polycondensate coatings have a thickness between 5and 30μm.
 16. The varnished metal wire according to claim 1, comprisingof one or more coatings of other materials or mixtures of othermaterials than silicid acid (hetero) polycondensates.
 17. A coilcomprising the varnished metal wire according to claim
 1. 18. A windingcomprising the varnished metal wire according to claim
 1. 19. Thevarnished metal coil wire of claim 1 wherein the varnish coating has atan δ-glass transition temperature of at least about 200° C.
 20. Thevarnished metal coil wire of claim 1 wherein the varnish coating has anabrasion resistance measured by scraping force of at least about 8 N.